SERS detection of multiple antimicrobial-resistant pathogens using nanosensors

Successful pathogen detection is crucial for public health as the threat of infectious disease is dramatically increasing globally due to bacteria developing resistance to many antimicrobial drugs. The increase in bacterial infections has led to urgent demands for simpler, faster, and more reliable detection methods to be developed allowing the most appropriate therapy to be provided. Surface enhanced Raman scattering (SERS) is an analytical technique which has gained a great deal of interest for biosensing due to its sensitivity, selectivity, and multiplexing capabilities. A new bionanosensor has been developed for the isolation and detection of multiple bacterial pathogens via magnetic separation and SERS. This novel assay format involves using lectin functionalized magnetic nanoparticles for capture and isolation of bacteria from the sample matrix followed by specifically detecting bacterial pathogens using SERS active nanoparticles functionalized with antibodies which are strain specific. Therefore, the sample is captured using a "magnetic plug" and interrogated with a laser allowing simple and fast optical detection. Three bacterial pathogens (Escherichia coli, Salmonella typhimurium, and methicillin-resistant Staphylococcus aureus) were successfully isolated and detected, with the lowest concentration for each of the strains detected at just 10¹ colony forming units per mL (CFU/mL). In addition to single pathogen detection, a mixture of all three bacterial strains was isolated and identified within the same sample matrix using SERS with the triplex detection also being confirmed using principal component analysis. Herein, we demonstrate that this multiplexed bionanosensor is capable of providing rapid and sensitive discrimination of bacterial pathogens both individually, and within a multiplex system, offering opportunities for future point of care devices and advancements in biomedical applications.